In direct-injection internal combustion engines, fuel-injection systems are increasingly used that have a high-pressure collecting chamber (common rail). As a result of a high-pressure pump that permanently acts upon the high-pressure collection chamber, a virtually constant, high pressure level is maintained in the chamber. The fuel stored at high pressure in the high-pressure collection chamber is conveyed to the fuel injectors, which are assigned individually to the individual combustion chambers of the internal combustion engine. Therefore, increased demands with respect to high-pressure resistance are being placed on the fuel injectors, the supply lines from the high-pressure collection chamber as well as their connection points, and the supply system within the injector.
German Patent 196 50 865 A1 relates to a solenoid valve for controlling a fuel injector. A solenoid valve is proposed, whose magnet armature is configured in multiple parts, and which has an armature disk as well as an armature pin, which is guided in a sliding bloc. In order to avoid a backlash of the armature disk after the solenoid valve is closed, a damping device is provided on the magnet armature. Using a device of this type, it is possible to precisely maintain and reproduce the necessary short switching of the solenoid valve. The solenoid valve is designed for use in injection systems having a high-pressure collection chamber (common rail).
In accordance with this solution, a connection for a supply line from the high-pressure collection chamber is accommodated on the valve housing so as to be oriented diagonally, thus making it possible to achieve an improvement in the high-pressure resistance of a fuel injector. However, the improvement in the high-pressure resistance that can be achieved using this measure remains unsatisfactory, because, with respect to a further increase in the pressure level in the high pressure collection chamber (common rail), the increase in high-pressure resistance achieved by this measure may well be exhausted in the wake of further developmental advances.
In contrast to the configuration of a single supply-line bore leading to the central bore, or to the annular chamber of a fuel injector, the solution according to the present invention proposes executing a plurality of supply-line bores that have an essentially smaller diameter than that of the bore, or the annular chamber. The advantage of this solution, which favorably influences the high-pressure resistance of a fuel injector, can be seen in the fact that the two or more supply-line bores can be configured as having an essentially smaller bore diameter. The greater the difference that can be maintained between the diameters of the supply-line and the central bore, or of the annular chamber in the fuel injector, the more favorable will be the high-pressure resistance in the fuel injector.
With regard to the central bore, or to an annular chamber configured in the injector body of the fuel injector, the supply-line bores can run parallel to each other in the injector body; in addition, it is also possible to arrange the supply-line bores to run at an angle xcex4 diagonal to the central bore, or to the annular chamber of the fuel injector. Angle xcex4 can be selected so as to be between 0xc2x0 (the parallel position of the supply-line bores in the injector body with respect to each other) and a position in which the supply-line bores run tangentially with respect to the wall of the central bore, or of the annular chamber in the injector body, and discharge into the annular chamber or the central bore.
In addition to two or more supply-line bores leading to the central bore of the injector body, or its annular chamber, it is possible to configure in the injector body a further bore of a smaller diameter that directly acts upon the nozzle supply-line leading to the injection nozzle, it being possible to configure the bore leading to the two aforementioned supply-line bores in the xc2xd hole pattern, above or below at a distance, corresponding, for example, to half the distance between the supply-line bores in the injector body.
Using this configuration of the two or more supply-line bores in the interior of the injector body downstream of the connection point for the supply-line from the high-pressure collection chamber (common rail), the high-pressure resistance of the injector can be significantly increased. If the supply-line bores in the interior of the injector body are additionally subjected to an interior rounding-off, it is possible to achieve further resistance reserves, which make possible a further increase in the pressure level in the high-pressure injection system having a high-pressure collection chamber (common rail).